The Future of Fire

As thousands of acres burn in southern Idaho wildfires each year and are threatening the landscape, University of Idaho researchers are studying how these wildfires are affecting the arid ecosystems, how post-fire rehabilitation efforts are affecting ecosystem recovery and what this might mean in future climates.

At the heart of the study is the sagebrush steppe that once covered vast acres of Idaho and the Great Basin and is being threatened by wildfire, overgrazing, recreation and invasive plants. Beth Newingham, an assistant professor in the UI College of Natural Resources’ Department of Forest, Rangeland and Fire Sciences, and her students are investigating ways to better understand how this ecosystem works and aiding state and federal land officials as they manage these drylands now and in the future.

Fire in a Changing Climate

At the Morley Nelson Snake River Birds of Prey National Conservation Area south of Boise, doctoral student Alex Suazo maintains 10 sites where he studies how future climate change, such as increased temperature and decreased rain, could affect how well newly seeded plants take hold after wildfire. The federal Bureau of Land Management and other agencies invest millions of dollars in reseeding land after fires, but such efforts may not be fully successful if the new seedlings don’t thrive, whether due to plant type or drought conditions.

“Climate change is going to drive whether things recover and whether or not those efforts to reseed are going to be effective,” Newingham says. Suazo follows the growth and survival of seedlings under different simulated climate conditions. He also has designed his sites to gather information on soil moisture and temperature.

“With this climate and plant data, we could develop predictive models to see how these species will perform in the future,” he says. Recovery efforts may also be thwarted if the plants that do succeed fuel further burns. Suazo says preliminary results of his research show cheatgrass, an invasive grass that creates large fuel loads, may thrive in drought conditions.

Fire in a Changing Landscape

Another of Newingham’s doctoral students, Chris Bowman-Prideaux, is examining how fires may drive the change from sagebrush to cheatgrass and other plants.

“My ultimate question is what is the threshold at which sites switch from a native-dominated plant community to a non-native community,” he says. “How many fires does it take? Does it matter if it’s reseeded afterward? Does the reseeding increase the duration between fires?”

A southern Idaho research site that has been through two wildfires with no reseeding efforts is shown here.

Bowman-Prideaux is studying 42 sites that have experienced between zero and six fires in the past 53 years. Some have been reseeded, while others have not.

His results so far show that the time between fires decreases with each time a site burns. Reseeding method also matters. After five fires, sites where reseeding efforts included both dropping seed from a helicopter and using tractors to till and plant the seed, burn again in three years, while sites that were not reseeded burn again after seven years. When only one method is used, sites burn again in about 10 years.

Fire and Changing Soil

Adding another layer to her team’s work, Newingham’s own research focuses on the effects of fire and ecosystem change on the soil beneath the plants.

Biological soil crust – a layer of moss, lichen and cyanobacteria that protects soil from erosion and provides nutrients and water – is often neglected in post-fire rehabilitation efforts, Newingham says. “In my mind, one of the first things to look at is soil. If you don’t have soil, you don’t have plants.”

Fire plays a major role in crust and vegetation loss on the sagebrush steppe, which can lead to severe dust storms. Dust problems can lead to dangerous highway driving conditions, cause human respiratory problems and cause early snowmelt that effects water quality.
The research in the Newingham Lab suggests that lower elevation sagebrush steppes of southern Idaho that historically experienced fire regimes with more than 100 years between fires may not be able to recover in a warmer climate and may lead to a dustier world.

“These desert systems already have a hard time recovering from disturbance with such little water – and climate change and invasive species will make recovery more difficult and likely increase the occurrence of fire and dust storms,” Newingham says. “Fire has already increased throughout the southern portion of Idaho, and Dust Bowl-like conditions are being seen more and more.”